AB0079 THERAPEUTIC EFFECT OF ANTIGEN B, A PROTEIN FROM ECHINOCOCCUS GRANULOSUS, IN EXPERIMENTAL ARTHRITIS
Authors: M. L. Gasparini Vieira, M. Farinon, R. T. Pedo, V. Schuck Clarimundo, A. Zaha, H. Bunselmeyer Ferreira, K. Mariante Monteiro, P. Gnieslaw de Oliveira, R. Xavier
Journal: Annals of the Rheumatic Diseases (2022)

Background Antigen B (AgB) is a lipoprotein secreted in the hydatic cyst by Echinococcus granulosus larval stage and seems to be responsible for regulating the immune balance of host via Th2 response to promote survival of the parasite. A Th2 response can suppress the pro-inflammatory Th1 response generated in several immunopathologies, such as rheumatoid arthritis. Objectives To evaluate the anti-inflammatory and immunomodulatory effects of AgB in mice models of Zymozan-induced arthritis (ZIA), Antigen-induced arthritis (AIA) and Collagen-induced arthritis (CIA). Methods In all models, mice were divided into three groups: vehicle (saline), AgB 2 μg and AgB 10 μg (intraperitoneal once a day). In ZIA, arthritis was induced in Balb/c mice with an intra-articular (ia) injection of zymosan in the left knee joint thirty minutes after treatment. Nociception was analyzed over a 6h period and mice were euthanized 6h after arthritis induction to assess leukocyte migration into the joint. In AIA, Balb/C mice were sensitized by subcutaneous (sc) injection of methylated bovine serum albumin (mBSA) on day 0. Booster was administered on days 7 and 14. On day 21, arthritis was induced by ia injection of mBSA in the left knee joint. The treatment was performed 24h and 30min before the ia injection of mBSA. Nociception was analyzed over a 24h period and mice were euthanized 24h after arthritis induction to assess leukocyte migration into the joint. Male DBA/1J mice had CIA by subcutaneous injection of an emulsion containing Freund’s adjuvant and bovine collagen type II on days 0 and 18. The treatment took place between the 18th and 45th day after induction, as well as the evaluation of clinical arthritis score and nociception. Serum concentrations of IL-2, IL-4, IL-6, IL-10, IL-17, IFN-γ and TNF were evaluated in AIA and CIA. Results In ZIA, both doses of AgB diminished leukocytes migration to the knee joint compared with vehicle (AgB 2µg: 5.8±2.7; AgB 10µg: 5.6±2.7; vehicle: 4.8±3.1, p&lt;0.05), but did not affect nociception. In AIA, both doses of AgB reduced nociception (AgB 2µg: 7.3±1.6; AgB 10µg: 7.2±1.6; vehicle: 6.0±2.1, p&lt;0.01). Moreover, treatment with 2 μg of AgB inhibited in 70% the neutrophils migration (12.0±9.0, p&lt;0.001) as well as it was reduced in mice treated with 10 μg of AgB as much as 58% (8.9±7.5, p&lt;0.001), compared with control/vehicle (55.9±30.9). In addition, both doses reduced serum levels of IL-6 (AgB 2µg: 2.85±2.63; AgB 10µg: 3.10±3.18; vehicle: 27.07±30.28, p&lt;0.01) and the dosage of 2 μg reduced the levels of IFN-γ (AgB 2µg: 0.53±0.27; vehicle: 1.47±0.46, p&lt;0.05). In CIA, AgB treatment did not affected clinical score of arthritis (AgB 2µg: 4.6±3.8; AgB 10µg: 2.6±2.9; vehicle: 4.8±3.8, p&gt;0.05), but the 2 μg dose improved nociception at day 32 after disease induction (7.1±1.2, p&lt;0.05) and diminished serum levels of IL-6 (AgB 2µg: 68.9±71.8; vehicle: 475.7±362.3, p&lt;0.05;) and TNF (AgB 2µg: 49.3±31.1; vehicle: 115.9±19.58; p&lt;0.01), while the dose of 10 μg improved nociception at days 25, 32 and 34 after CIA induction (7.2±1.2, p&lt;0.05). Conclusion These results suggest an effect of AgB on the initial pathophysiology of arthritis, reducing the influx of inflammatory cells to the knee joints of mice with acute arthritis. It also showed analgesic and anti-inflammatory potential on murine models of rheumatoid arthritis, highlighting the immunomodulatory role of parasitic helminth proteins on immune-mediated diseases. References [1]Monteiro KM, Cardoso MB, Follmer C, da Silveira NP, Vargas DM, Kitajima EW, et al. Echinococcus granulosus antigen B structure: subunit composition and oligomeric states. PLoS Negl Trop Dis. 2012. [2]Mesquita Júnior, D. et al. Immune system - part II: basis of the immunological response mediated by T and B lymphocytes. Revista Brasileira De Reumatologia, v. 50, n. 5, p. 552–580, 2010. Acknowledgements We thank the Animal Experimentation Unit from the Hospital de Clínicas de Porto Alegre (HCPA) for their help during animal experimentation. Disclosure of Interests None declared